Semiconductor devices are continuously driven to be more productive, occupy less space, consume less power, and cost less. These advances continually cause new design limitations and liabilities. By reducing the device feature size, the device capacity is increased, but the vulnerability to particle damage is also increased. The structure and operation of semiconductor process machinery is a key focus of the effort to reduce particulate contamination during semiconductor device fabrication. Particulate contamination is a major concern when dealing with the deposition of metal films including refractory metal films which are commonly used as diffusion barriers and for other purposes in modern semiconductor devices.
As metal films are deposited on semiconductor wafers within a fabrication system, metal films are also necessarily deposited on portions of the inner surfaces of the semiconductor processor equipment. The metal deposited on the equipment must adhere to the equipment to prevent particulate contamination of the wafers being processed in the equipment. When the metal deposited on the inner surface of the equipment separates from the equipment, the metal film is said to have delaminated. Delaminated metal from the interior surfaces of process equipment can be a major cause of particulate contamination which can dramatically degrade the process yields associated with device fabrication. For a variety of reasons, process equipment is usually fabricated from a base material such as, for example, stainless steel. For films such as aluminum or titanium, the adhesion to the stainless steel shielding within the process chamber is good. However, refractory films such as molybdenum or titanium-tungsten (Ti-W) are notorious for refusing to adhere to these surfaces due to the high stresses of these films and the incompatibilities of the metal grain sizes between the refractory film and the stainless steel forming the inner surface of the process equipment.
Accordingly, a need has arisen for methods and systems which can prevent the particulate contamination associated with delamination of deposited films from the interior of semiconductor processing equipment used to deposit metallic films.